Derivatives of 6-bromo penicillanic acid

ABSTRACT

2β-Chloromethyl-2α-methylpenam-3α-carboxylic acid sulfone and salts and esters thereof were synthesized and found to be potent inhibitors of β-lactamases.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of my prior, copending application Ser. No. 113,894 filed Jan. 21, 1980, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The novel chemicals of the present invention include potassium 2β-chloromethyl-2α-methylpenam-3α-carboxylate sulfone which is useful as an inhibitor of β-lactamases.

2. Description of the Prior Art

The presumed association between the resistance shown by β-lactam antibiotics to certain bacteria and the ability of those bacteria to produce β-lactamases has led to an intensive search for β-lactamase inhibitors. Clavulanic acid is an example of such a compound presently under intensive study. Another β-lactamase inhibitor has in its acid form the structure ##STR1## and is disclosed in European Patent Application 2927 published July 11, 1979.

The compound having the structure ##STR2## is disclosed in U.S. Pat. Nos. 4,036,847, 4,009,159, 3,993,646, 3,989,685 and 3,954,732.

For a corresponding sulfoxide having the 6-amino group acylated and, for example, the structure ##STR3## see Tetrahedron Letters, 38:3303-3310 (1975) and Kukolja et al., J. Org. Chem., 41, 2276-2279 (1976).

1,1-Dioxides of benzylpenicillin, phenoxymethylpenicillin and certain esters thereof have been disclosed in U.S. Pat. No. 3,197,466 and 3,536,698, and in an article by Guddal et al., Tetrahedron Letters, No. 9, 381 (1962). Harrison et al., in the Journal of the Chemical Society (London), Perkin I, 1772 (1976), have disclosed a variety of penicillin 1,1-dioxides, including methyl phthalimidopenicillanate 1,1-dioxide and methyl 6,6-dibromopenicillanate 1,1-dioxide. U.S. Pat. No. 3,544,581 discloses 6-aminopenicillanic acid 1-oxide.

For a brief review of esters of penicillins, see U.S. Pat. No. 3,996,236. Recent U.S. Pat. Nos. on esters of ampicillin and similar derivatives include 4,217,274, 4,081,546, 4,046,759, 4,036,829, 3,963,704, 3,954,735, 3,951,954, 3,941,774, 3,939,180, 3,931,150, 3,873,521, 3,860,579 and 3,697,507.

Recent U.S. Pat. Nos. on compounds (e.g. esters) or mixtures containing two like or unlike β-lactam derivatives include 4,181,659, 3,928,595, 3,869,449 and 3,867,538.

U.S. Pat. No. 4,155,912 describes 2-penem-3-carboxylic acid compounds having the formula ##STR4## and esters and salts, and see also Farmdoc Abstracts 82090A, 10336B and 44337B.

The compound (under the number CP-45899) having the structure ##STR5## is an irreversibly acting β-lactamase inhibitor with excellent solution stability. It has weak antibacterial activity and potentiates the in vitro and in vivo activities of ampicillin versus β-lactamase-producing strains [A. R. English et al., Antimicrobial Agents and Chemotherapy, 14, 414-419 (1978), Aswapokee et al., J. Antibiotics 31(12), 1238-1244 (Dec. 1978) and Derwent's Farmdoc Abstracts 89627A and 73866B].

Cignarella and associates [J. Org. Chem. 27, 2668 (1962)] reported the first deamination of 6-aminopenicillanic acid (6-APA) (1). When treated with sodium nitrite and hydrochloric acid, 6-APA was converted to 6-chloropenicillanic acid (96), isolated as the dibenzylethylenediamine salt. Substitution of hydrobromic acid in the reaction gave the 6-bromo derivative (97). Both deaminated products were devoid of microbiological activity against M. pyogenes aureus 209P. ##STR6##

Evrard and co-workers [Nature, 201, 1124 (1964)] prepared the methyl esters of (96) and (97) and showed that (97) could be hydrogenated to penicillanic acid (98). Their study emphasized the value of gas chromatography in the separation of penicillanates including methyl penicillanate (99). ##STR7##

Compound 98 above is also described in U.K. Pat. No. 1,072,108 (1967).

6β-Bromopenicillanic acid is claimed in U.S. Pat. No. 4,180,506 and described as potentiating the in vitro activity of benzylpenicillin and ampicillin against certain bacteria.

According to U.S. Pat. Nos. 4,203,992 and 4,203,993 (2S,5R,6S)-6β-Bromo-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid, S,S-dioxide, physiologically acceptable salts thereof and readily hydrolyzable ester thereof inhibit the action of the β-lactamase enzyme RTEM.

EPO 13,617 states that its invention relates to a process for the preparation of certain penicillin derivatives which are useful as β-lactamase inhibitors. The compounds which may be prepared by the process of this invention have formula (1), or a pharmaceutically acceptable salt or ester thereof: ##STR8## wherein R represents hydrogen, halogen, C₁₋₆ alkylthio, C₁₋₆ alkyl or alkyl substituted with phenyl, carboxy, C₁₋₆ alkoxycarbonyl, hydroxy or C₁₋₆ alkylthio, and n is zero, 1 or 2. In addition certain of the compounds produced by the process of the invention are novel compounds. Claim 1 therein reads as follows:

1. A compound of the formula (II): ##STR9## or a pharmaceutically acceptable salt or in-vivo hydrolysable ester thereof wherein X is a bromine or chlorine atom, and n is zero, 1 or 2, when substantially free from the corresponding 6α-substituted compound.

The compound (under the number CP-45,899) having the structure ##STR10## is an irreversibly acting β-lactamase inhibitor with excellent solution stability. It has weak antibacterial activity and potentiates the in vitro and in vivo activities of ampicillin versus β-lactamase-producing strains [see Derwent's Farmdoc Abstracts 89627A and 73866B].

It is disclosed by B. Baltzer et al., Mutual Pro-Drugs of β-Lactam Antibiotics and β-Lactamase Inhibitors, J. Antibiotics, 33(10), 1183-1192 (1980) that the principle of combining β-lactam antibiotic with a β-lactamase inhibitor in a single molecule functioning as pro-drug for the two active components is illustrated by the linked esters 3 and 4 in which ampicillin and mecillinam, respectively, are combined with the β-lactamase inhibitor penicillanic acid sulfone. It is shown that in man these esters are excellently absorbed from the gastro-intestinal tract and after absorption hydrolyzed with simultaneous liberation of the active components. As a result high blood and tissue levels of antibiotic and β-lactamase inhibitor in a balanced ratio are attained. The advantages of "mutual pro-drugs" over simple combinations are discussed.

Esters 3 and 4 referred to therein have the structures ##STR11##

The following publications were discussed in the Baltzer et al. publication:

(1) Von Daehne, W.; E. Frederiksen, E. Gundersen, F. Lund, P. Morch, H. J. Petersen, K. Roholt, L. Tybring & W. O. Godtfredsen: Acyloxymethyl esters of ampicillin. J. Med. Chem. 13: 607-612, 1970

(2) Binderup, E.; W. P. Godtfredsen & K. Roholt: Orally active cephaloglycin esters. J. Antibiotics 24: 767-773, 1971

(3) Wheeler, W. J.; W. E. Wright, V. D. Line & J. A. Frogge: Orally active esters of cephalosporin antibiotics. Synthesis and biological properties of 7-(D-2-amino-2-phenylacetamido)-3-[5-methyl-(1,3,4-thiadiazol-2-yl)thiomethyl]-3-cephem-4-carboxylic acid. J. Med. Chem. 20: 1159-1164, 1977

(4) Wheeler, W. J.; D. A. Preston, W. E. Wright, G. W. Huffman, H. E. Osborne & D. P. Howard: Orally active esters of cephalosporin antibiotics. 3. Synthesis and biological properties of aminoacyloxymethyl esters of 7-[D-(-)-mandelamino]-3-[[(1-methyl-1Htetrazol-5-yl)thio]methyl]-3-cephem-4-carboxylic acid. J. Med. Chem. 22: 657-661, 1979

(5) Wright, W. E.; W. J. Wheeler, V. D. Line, J. A. Frogge & D. R. Finley: Orally active esters of cephalosporin antibiotics. II. Synthesis and biological properties of the acetoxymethyl ester of cefamandole. J. Antibiotics 32: 1155-1160, 1979

(6) Roholt, K.: Pharmacokinetic studies with mecillinam and pivmecillinam. J. Antimicrob. Chemother. 3 (Suppl. B): 71-81 1977

(7) Foulds, G.; W. E. Barth, J. R. Bianchine, A. R. English, D. Girard, S. L. Hayes, M. M. O'Brien & P. Somani: Pharmacokinetics of CP-45,899 and pro-drug CP-47,904 in animals and humans. Current Chemother, & Infect. Disease 1980: 353, 1980

(8) Aswapokee, N. & H. C. Neu: A sulfone β-lactam compound which acts as a β-lactamase inhibitor. J. Antibiotics 31: 1238-1244, 1978

(9) Engberg-Pedersen, H: Empirical equation for pharmacokinetic analysis of drug serum levels after oral application. Antimicr. Agents & Chemoth. 6: 554-562, 1974

(10) Jordan, M. C.; J. B. De Maine & W. M. M. Kirby: Clinical pharmacology of pivampicillin as compared with ampicillin. Antimicr. Agents & Chemoth.-1970: 438-441, 1971

(11) Godtfredsen, W. O.: U.S. Pat. No. 3,869,449, 1975

(12) Christensen, B. G. & W. J. Leanza: U.S. Pat. No. 3,931,150, 1976

(13) Evrard, E.; M. Claesen & H. Vanderhaeghe: Gas chromatography of penicillin and penicillanic acid esters. Nature 201: 1124-1125, 1964

(14) English, A. R.; J. A. Retsema, A. E. Girard, J. E. Lynch & W. E. Barth: GP-45,899, a beta-lactamase inhibitor that extends the antibacterial spectrum of betalactam: Initial bacteriological characterization. Antimicro. Agents & Chemoth. 14: 414-419, 1978

It is stated in GB 2044255 published Oct. 15, 1980 that the invention therein relates to hitherto unknown compounds of the general formula 1: ##STR12## in which R₁ stands for a phenyl, 4-hydroxyphenyl, 1,4-cyclohexadienyl or a 3-thienyl group; R₂ represents a primary amino or a carboxy group; R₃ is a hydrogen atom, or a lower alkyl, aryl or aralkyl radical, and A stands for a radical of a β-lactamase inhibitor containing a β-lactam ring as well as a carboxy group, A being connected via the carboxy group.

The new compounds are useful in the treatment of bacterial infections and are in particular strongly active against β-lactamase producing bacteria. See also Farmdoc abstracts 60773C and 60776C.

SUMMARY OF THE INVENTION

The present invention provides the acid having the formula ##STR13## or a pharmaceutically acceptable salt of said acid or an easily hydrolyzed ester of said acid.

The pharmaceutically acceptable salts referred to above include nontoxic metallic salts such as sodium, potassium, calcium and magnesium, the ammonium salt and substituted ammonium salts, e.g. salts of such nontoxic amines as trialkylamines (e.g. triethylamine), procaine, dibenzylamine, N-benzyl-β-phenethylamine, 1-ephenamine, N,N'-dibenzyl-ethylenediamine, dehydroabietylamine, N,N'-bis(dehydroabietyl)ethylenediamine, N-(lower)alkylpiperidine (e.g. N-ethylpiperidine) and other amines which have been used to form pharmaceutically acceptable salts of penicillins and cephalosporins. The most preferred salts are the alkali metal salts, i.e. the sodium and potassium salts, and the ammonium salt.

As used herein the term "physiologically hydrolyzed esters" refers to those pharmaceutically acceptable esters known in the art to hydrolyze to the free acid form in vivo. Examples of suitable physiologically hydrolyzed esters include phenacyl, acetoxymethyl, pivaloyloxymethyl, α-acetoxyethyl, α-acetoxybenzyl, α-pivaloyloxyethyl, phthalidyl(3-phthalidyl), indanyl(5-indanyl), methoxymethyl, benzoyloxymethyl, α-ethylbutyryloxymethyl, propionyloxymethyl, valeryloxymethyl, isobutyryloxymethyl, 6-[(R)-2-amino-2-phenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carbonyloxymethyl and 6-[(R)-2-amino-2-p-hydroxyphenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carbonyloxymethyl. The preferred esters are the acetoxymethyl, pivaloyloxymethyl, methoxymethyl, phthalidyl, 5-indanyl, 6-[(R)-2-amino-2-phenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carbonyloxymethyl and 6-[(R)-2-amino-2-p-hydroxyphenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carbonyloxymethyl.

There is further provided by the present invention the process for the production as the desired product of the acid having the formula ##STR14## or a pharmaceutically acceptable salt of said acid which comprises the consecutive steps of

(a) catalytically hydrogenating, as with a precious metal catalyst such as palladium, an ester having the formula ##STR15## wherein R¹ is benzyl or substituted benzyl and then

(b) subjecting the hydrogenated product to oxidation to produce said desired acid or salt thereof and then, if desired,

(c) esterifying said acid or salt thereof to produce an easily hydrolyzed ester of said acid.

There is further provided by the present invention the process for the production as the desired product of the acid having the formula ##STR16## or a pharmaceutically acceptable salt of said acid which comprises the consecutive steps of

(a) oxidizing, as with KMnO₄, H₂ O₂ or like peroxide or peracid, an ester having the formula ##STR17## to produce an ester sulfone having the formula

(b) reacting said ester sulfone with a metal in acid, as with zinc in glacial acetic acid, to produce said desired acid or salt and then, if desired,

(c) esterifying said acid or salt thereof to produce an easily hydrolyzed ester of said acid.

A wide variety of oxidants known in the art for the oxidation of sulfides to sulfones can be used. However, particularly convenient reagents for alkali metal permanganates, e.g. potassium permanganate, and organic peracids, e.g. 3-chloroperbenzoic acid.

Particularly useful protecting groups for R¹ are the benzyl group and substituted benzyl groups, especially 4-nitrobenzyl. Benzyl and substituted benzyl groups can be removed conveniently by catalytic hydrogenation. In this case, a solution in an inert solvent of the compound of the formula A, wherein R¹ is benzyl or substituted benzyl, is stirred or shaken under an atmosphere of hydrogen, or hydrogen mixed with an inert diluent such as nitrogen or argon, in the presence of a catalytic amount of a hydrogenation catalyst. Convenient solvents for this hydrogenation are lower-alkanols, such as methanol; ethers, such as tetrahydrofuran and dioxan; low molecular weight esters, such as ethyl acetate and butyl acetate; water; and mixtures of these solvents. However, it is usual to choose conditions under which the starting material is soluble. The hydrogenation is usually carried out at a temperature in the range from about 0° to about 60° C. and at a pressure in the range from about 1 to about 100 kg./cm.². The catalysts used in this hydrogenation reaction are the type of agents known in the art for this kind of transformation, and typical examples are the noble metals, such as nickel, palladium, platinum and rhodium. The catalyst is usually present in an amount from about 0.01 to about 2.5 weight-percent, and preferably from about 0.1 to about 1.0 weight-percent, based on the compound of formula A. It is often convenient to suspend the catalyst on an inert support; a particularly convenient catalyst is palladium suspended on an inert support such as carbon. Additionally it is usual to buffer the reaction mixture in order to operate at a pH in the range from about 4 to 9, and preferably from 6 to 8. Borate and phosphate buffers are commonly used. The reaction typically takes about one hour.

There is further provided by the present invention the esters having the formula ##STR18## wherein R is ##STR19## wherein R¹ is hydrogen or hydroxy and R² is hydrogen, hydroxy, methyl, methoxy or chloro and preferably the ester having the formula ##STR20## and the ester having the formula ##STR21## and the process for producing such an ester which comprises the treatment with acid of a solution of a compound having the formula ##STR22## wherein R is ##STR23## wherein R⁴ is hydrogen or hydroxy and R⁵ is hydrogen, hydroxy, methyl, methoxy or chloro and R¹ is alkyl, aralkyl or aryl, R² is hydrogen, alkyl, aralkyl or aryl and R³ is alkyl, aralkyl, aryl, alkoxy, aralkoxy, aryloxy or ##STR24## wherein R⁴ and R⁵ are each hydrogen, alkyl, aralkyl or aryl or, when taken together with the nitrogen atom, are piperidino or morpholino with said treatment with acid preferably being carried out in an organic solvent such as acetone or chloroform or in aqueous or partly aqueous solution and preferably between pH 1 and pH 5 at room temperature.

It is further preferred that, in the amino-protecting group, R¹ is methyl, R² is hydrogen and R³ is methoxy, ethoxy or methyl; this requires the use of methyl acetoacetate, ethyl acetoacetate or acetylacetone.

In the removal of the α-amino-protecting group it is preferred that use be made of a strong mineral acid such as hydrochloric acid or of formic acid.

There is further provided by the present invention as a novel intermediate an ester having the formula ##STR25## wherein R is benzyl or substituted benzyl, and preferably p-nitrobenzyl, and the process for its production which comprises heating, preferably at reflux, a compound having the formula ##STR26## wherein R is benzyl or substituted benzyl and preferably p-nitrobenzyl, in an inert, anhydrous organic solvent, preferably dioxane, in the presence of large, and preferably equimolar, amounts of a weak tertiary amine, preferably quinoline, and an acid chloride, preferably benzoyl chloride, until the reaction is substantially complete.

There is provided by the present invention in addition as a novel intermediate an ester having the formula ##STR27## wherein R is benzyl or substituted benzyl, and preferably p-nitrobenzyl, and the process for its production which comprises oxidizing a solution in an inert solvent, preferably methylene chloride, of a compound having the formula ##STR28## wherein R is benzyl or substituted benzyl, and preferably p-nitrobenzyl, at about room temperature by the use of a peracid, preferably m-chloroperoxybenzoic acid.

There is further provided by the present invention as a novel intermediate the ester having the formula ##STR29## the process for its production which comprises oxidizing a solution in an inert solvent, preferably methylene chloride, of a compound having the formula ##STR30## at about room temperature by the use of an oxidizing agent such as KMnO₄, H₂ O₂ or like peroxide or, preferably a peracid, preferably m-chloroperoxybenzoic acid.

"Skellysolve B" is a petroleum ether fraction of b.p. 60°-68° C. consisting essentially of n-hexane ("Skellysolve" is a trade name of the Skelly Oil Co.).

The following examples are provided solely for the purpose of illustrating the preparation of representative compounds of the present invention and are not to be construed as limiting the invention.

EXAMPLE 1 Preparation of Potassium 2β-Chloromethyl-2α-methylpenam-3α-carboxylate Sulfone (BL-P2013) ##STR31## 6α-Bromopenicillanic Acid S-Sulfoxide (1)

1. Dissolve 30 g (37.5 mmole) 6α-bromopenicillanic acid N,N'-dibenzylethylenediamine salt [G. Cignarella et al., J. Org. Chem. 27, 2668 (1962) and E. Evrard, Nature 201, 1124 (1964)] in 330 ml of methylene chloride. Agitate and cool to 0° C.

2. Slowly add 13 ml (156 mmole) concentrated hydrochloric acid into the methylene chloride solution. The precipitation of dibenzylethylenediamine HCl salt (DBED.HCl) takes place within a minute. Stir the slurry at 0°-5° C. for 10 minutes.

3. Filter to remove the DBED.HCl precipitate through a precoated diatomaceous earth ("Dicalite") filter. Wash the cake with 150 ml of methylene chloride. The filtration should be completed as quickly as possible. Avoid holding the acidic methylene chloride solution for a prolonged period. There may be some filtration problems because of the fine nature of the precipitate. Addition of filter aid to the slurry may be helpful.

4. Wash the combined methylene chloride filtrate and wash with 60 ml of cold water. Agitate 5 minutes and discard the aqueous phase. The pH of the wash is 2.0-2.3.

5. The methylene chloride solution containing 6α-bromopenicillanic acid is concentrated under reduced pressure to a volume of 65-80 ml. Cool and stir the solution to 5° C.

6. With vigorous agitation cautiously add 13 ml (86.9 mmoles) of 40% peracetic acid over a period of 30 minutes. The reaction is exothermic. Maintain temperature between 15°-18° C. with ice bath cooling. The sulfoxide begins to crystallize after 10 ml peracetic acid is added. Cool and stir the slurry at 0°-5° C. for two hours.

7. Filter and wash the snow white cake with the following sequence: 10 ml 5° C. water, then 10 ml 0°-5° C. methylene chloride, and finally wash with 15 ml of heptane.

8. Dry the cake in 45° C. air oven to constant weight, about 6-10 hours should be sufficient. Extended heating may generate a trace of pinkish color. The weight of 1 is about 16.26 gm, 73.24% yield.

9. The reaction mix and final product may be monitored by TLC using 15 toluene/4 acetone/1 acetic acid (HAC) or 8 acetone/8 methanol/3 toluene/1 HAC solvent systems. The final product should be analyzed by NMR and IR.

p-Nitrobenzyl 6α-bromopenicillanate S-Sulfoxide (2)

To a solution of 12 g (0.04 mole) of 6α-bromopenicillanic acid s-sulfoxide in 100 ml of acetone was added 7.5 g (0.041 mole) of potassium 2-ethylhexanoate. The salt was collected by filtration, washed with cold acetone and air dried to yield a total of 10 grams. The crystalline potassium salt was dissolved in 75 ml of dimethylacetamide and 7.8 g (0.04 mole) of p-nitrobenzyl bromide was added. The solution was stirred at 23° C. for 24 hours. The mixture was diluted with 500 ml of water and extracted with ethyl acetate. The ethyl acetate layer was washed four times with water and dried over anhydrous magnesium sulfate. The solvent was evaporated at 35° C. (15 mm) to an oil which crystallized. The light tan crystals of 2 were slurried with ether and collected by filtration to yield 9 g (70%) mp 124°-125° C. dec.

Anal. calc'd for C₁₅ H₁₅ BrN₂ O₆ S: C, 41.98; H, 3.05; N, 6.52: Found: C, 42.00; H, 3.48; N, 6.98.

IR(KBr): 1800(s), 1740(s), 1610(w), 1520(s), 1450(m), 1350(s), 1060(m), 740(m) cm⁻¹. H-NMR (60 mHz, DMSO): δ1.22 (s,3H), 1.6 (s,3H), 4.67 (s,1H), 5.2 (d,J˜1-5 Hz,1H), 5.45 (s,2H), 5.68 (d,J˜1-5Hz,1H), 7.5-8.5 (m,4H).

p-Nitrobenzyl 2β-chloromethyl-2α-methyl-6-bromopenam-3α-carboxylate (3)

A solution of 5 g (0.012 mole) of p-nitrobenzyl 6α-bromopenicillanate S-sulfoxide (2) in 120 ml anhydrous dioxane was heated at reflux under nitrogen for 4 hours with 1.5 g (0.012 mole) of quinoline and 1.6 g (0.012 mole) of benzoyl chloride. The solution was diluted with 600 ml of water and extracted with ethyl acetate. The ethyl acetate extract was washed with 5% sodium bicarbonate solution, 5% phosphoric acid solution and finally with water. The organic layer was dried over anhydrous magnesium sulfate and evaporated to an oil at 35° C. (15 mm). The oil crystallized and was collected, washed with ether, and finally with cold toluene to yield 3, 3.5 g (65%) mp 130°-135° C. dec.

Anal. calc'd for C₁₅ H₁₅ ClBrN₂ O₅ S: C, 40.06; H, 3.14; N, 6.23: Found: C, 40.19; H, 3.12; N, 6.75.

IR(KBr): 1792(s), 1740(s), 1610(w), 1520(s), 1353(s), 1280(m), 1025(w), 990(w), 750(w) cm⁻¹.

NMR (60 mHz, DMSO): δ1.45 (s,3H), 3.5-4.3 (m,2H), 5.05 (s,1H), 5.42 (s,2H), 5.5(d,J˜1.5 Hz,1H), 5.62 (d,J˜1.5 Hz,1H), 7.5-8.5 (m,4H).

p-Nitrobenzyl 2β-Chloromethyl-2α-methylpenam-6α-carboxylate Sulfoxide (4)

A solution of 1 g (0.0022 mole) of p-nitrobenzyl 3β-chloromethyl-2α-methyl-6α-bromopenam-3α-carboxylate (3) dissolved in 50 ml of methylene chloride was stirred with 473 mg of (0.0022 mole) of m-chloroperoxybenzoic acid. The solution was stirred at 23° C. for 3 hours. The methylene chloride was evaporated to 20 ml at 15 mm and 33° C. and the concentrated solution was diluted with 50 ml of heptane ("Skellysolve B"). The solvent was decanted and the residue was slurried with ether and (4) soon crystallized yield 250 mg, 24% mp 136°-137° C. dec.

Anal. Calc'd for C₁₅ H₁₄ BrClN₂ O₆ S: C, 38.68; H, 3.02; N, 6.02: Found: C, 39.14; H, 3.13; N, 5.96.

IR(KBr): 1800(s), 1760(s), 1520(s), 1350(s), 1200(s), 1050(m), 830(w), 740(w) cm⁻¹. H-NMR (60 mHz, DMSO): δ1.32 (s,3H), 3.8-4.5 (m,2H), 4.97 (s,1H), 5.25 (d,J˜1.5 Hz,1H), 5.45 (s,2H), 5.6 (d,J˜1.5 Hz,1H), 7.8-8.5 (m,4H).

Potassium 2β-Chloromethyl-2α-methylpenam-3α-carboxylate Sulfone (5) (BL-P2013)

To a solution of 7 g (0.015 mole) of p-nitrobenzyl 2β-chloromethyl-2α-methyl-6α-bromopenam-3α-carboxylate sulfoxide (4) in 150 ml of ethyl acetate was added a suspension of 4 g of 30% palladium on diatomaceous earth ("Celite") and 2.8 g of sodium bicarbonate in 150 ml of water. The mixture was hydrogenated for 3 hours at 50 psi. The catalyst was separated by filtration and the aqueous layer was separated and treated with 1.5 g of potassium permanganate in 50 ml of water. The mixture was stirred for 1 hour and 250 mg of sodium bisulfite was added. The mixture was filtered and the filtrate was adjusted to pH 2 with concentrated hydrochloric acid. The solution was lyophilized to give a white amorphous powder. The solid was extracted with ethyl acetate, evaporated to a volume of 20 ml and diluted with 100 ml of heptanes ("Skellysolve B"). White, hygroscopic, solid 2β-chloromethyl-2α-methylpenam-3α-carboxylic acid sulfone was collected. The acid was dissolved in acetone and treated with solid potassium 2-ethylhexanoate. A crystalline white salt precipitated to give, after filtration, 170 mg of 5 mp>140° C. dec.

Anal. calc'd for C₈ H₇ ClKNO₅ S.2H₂ O: C, 28.27; H, 3.24; N, 4.12: Found: C, 28.27; H, 3.69; N, 3.84.

IR(KBr): 1790(s), 1770(m), 1620(s), 1460(m), 1370(s), 1310(s), 1200(s), 1140(s), 955(m), 740(m) cm⁻¹. H-NMR (100 mHz, D₂ O): δ1.68(s,3H), 3.2-3.9 (m,J˜2 Hz, J˜4 Hz, J˜6 Hz,2H), 4.0-4.4 (m,2H), 4.3 (s,1H), 5.02 (d d, J˜4 Hz), (J˜2 Hz,1H).

EXAMPLE 2 Pivaloyloxymethyl 2β-Chloromethyl-2α-methylpenam-3α-carboxylate Sulfone

2β-Chloromethyl-2α-methylpenam-3α-carboxylic acid sulfone in dimethylformamide is treated with one equivalent of triethylamine and stirred to effect solution. Bromomethyl pivalate (1 equivalent) in dimethylformamide is then added. The resulting mixture is stirred at room temperature. The mixture is then clarified by filtration and the filtrate poured into ice water. The separated solid is collected by filtration, washed with water and dried to give the title ester.

The respective acetoxymethyl, methoxymethyl, acetonyl and phenacyl esters of the same acid are prepared by substituting in the method above for the bromomethyl pivalate used therein an equimolar weight of chloromethyl acetate, chloromethyl methyl ether, chloroacetone and phenacyl bromide, respectively.

EXAMPLE 3 Pivaloyloxymethyl 2β-Chloromethyl-2α-methylpenam-3α-carboxylate Sulfone BL-P2024 ##STR32##

To a stirred suspension of 14.6 g (0.0487 mol) of BL-P2013 (5) in 200 ml of acetone was added 4 ml of a 10% aqueous solution of sodium iodide and the mixture was brought to reflux on the steam bath. To this refluxing suspension was added 14.8 ml (0.1 mol) of redistilled chloromethyl pivalate (B.P. 34° C. at 7 mm Hg) all at once. The mixture was stirred at reflux for three hours and then cooled to room temperature (22° C.). The crystalline solids were collected by filtration, washed with 3×30 ml of acetone and the combined filtrates were evaporated in an oil in vacuo at <22° C. The oil was then taken up in 500 ml of ethyl acetate and washed once with water (200 ml) and once with saturated Na₂ SO₄ while being stirred with 2 g. of decolorizing carbon with cooling (ice bath). After 20 minutes the mixture was filtered through a diatomaceous (Dicalite) pad with suction and the pad was washed with 4×100 ml of ethyl acetate. The combined filtrates were concentrated in vacuo at 22° C. to an oil. The oil was then concentrated further at about 22° C. and <1 mm Hg to remove most of the residual chloromethyl pivalate. The remaining oil was then triturated twice with 50 ml portions of n-pentane and then left over the weekend in the cold room (about 10° C.) under n-pentane. The solid crystalline mass was then broken up to a solid powder under 40 ml of 4:1 mixture of ether-n-pentane. The product was then collected by filtration, washed with ether-pentane (1:1) then pentane and air dried. After drying in vacuo for four hours over P₂ O₅ there was obtained 13.37 g. of pivaloyloxymethyl 2β-chloromethyl-2α-methylpenam-3α-carboxylate sulfone (about 75% yld) M.P. 93°-95° C.

Anal. Calcd. for C₁₄ H₂₀ ClNO₇ S: C, 44.03; H, 5.27; N, 3.67: Found: C, 44.11; H, 5.08; N, 3.85.

EXAMPLE 4 Recrystallization of Potassium 2β-Chloromethyl-2α-methylpenam-3α-carboxylate Sulfone (BL-P2013)

To a mixture of 20 ml of n-butanol and one gram of BL-P2013 (5) was added water, one ml at a time, with shaking in a separatory funnel until a pale yellow solution was obtained. The clear solution was filtered through a fluted filter paper and the flask and filter paper washed with about 10 ml of 9:1 n-butanol-H₂ O and the combined filtrates were diluted with a further 20 ml of n-butanol. The resulting solution was placed in a round-buttomed flask on the roto-vap and evaporated under reduced pressure to approximately one half the original volume. The snow white crystalline product was collected by filtration, washed with 6×10 ml of acetone and air dried. Yield 810 mg. After vacuum drying 6 hours over P₂ O₅ at <1 mm Hg. there was obtained 800 mg M.P. 215° C. (dec.) (80% yld).

Anal. Calcd. for C₈ H₉ ClNO₅ SK.1H₂ O: C, 29.67; H, 3.39; N, 4.63; Cl, 10.94; K.F.H₂ O, 5.56. Found: C, 29.23; H, 3.38; N, 4.49; Cl, 10.74; K.F.H₂ O, 5.74.

This recrystallization procedure produces a crystalline monohydrate differing from the starting material which is essentially anhydrous.

EXAMPLE 5 ##STR33## See Chemical Abstracts 27, 2427¹ and 22, 382⁸ ; and GB 299064. ##STR34##

(a) A solution of chloromethyl chlorosulfate (0.115 mol) in 40 ml. dichloromethane is added dropwise, keeping the reaction temperature below 30° C., to a solution of compound 5 (0.1 mol) and potassium bicarbonate (0.3 mol) and tetrabutylammonium hydrogen sulfate (0.01 mol) in 200 ml. dichloromethane-water (1:1). At the end of the addition the mixture is stirred at room temperature for 30 minutes, the organic phase is separated and the aqueous phase is extracted with dichloromethane (50 ml.). The combined organic phases are dried (Na₂ SO₄) and evaporated in vacuo to give a residue which is dissolved in ether (150 ml.). Insoluble material is filtered off after adding diatomaceous earth and the filtrate is evaporated in vacuo to provide compound 7.

(b) To a suspension of compound 5 (1.5 g.) in dimethylformamide (12 ml.) there is added 1.6 g. bischloromethyl sulfate and the mixture is stirred at room temperature for 45 minutes. After dilution with ethyl acetate (50 ml.) the mixture is washed with water and then aqueous sodium bicarbonate, dried and evaporated in vacuo to leave compound 7 as an oil.

(c) To a solution of compound 5 (0.005 mol) in dimethylformamide (7.5 ml.) there is added triethylamine (0.007 mol) and chloroiodomethane (0.030 mol) and the mixture is stirred at room temperature for four hours. After dilution with ethyl acetate (30 ml.) the mixture is washed with water (3×10 ml.) followed by saturated aqueous sodium chloride (5 ml.), dried and evaporated in vacuo to leave compound 7 as an oil.

(d) To a mixture of compound 5 (0.15 mol) silver nitrate (0.15 mol) and silver oxide (7.5 g.) in acetonitrate (750 ml.) there is added chloroiodomethane (1.5 mol). After stirring for 48 hours at room temperature, the silver salts are filtered off and the filtrate is evaporated to dryness in vacuo. The residue is dissolved in ethyl acetate (200 ml.) and the solution is washed with saturated aqueous sodium chloride, filtered, dried and evaporated in vacuo to give compound 7.

Compound 7 and other intermediates and final products of the present invention are purified, if desired, by column chromatography, as on "Sephadex" LH20 using chloroform-hexane, 65:35 as the eluent for example or by silica gel chromatography, e.g. using Mallinckrodt CC-7 and hexane-ethyl acetate, 3:2 or ethyl acetate-petroleum ether, 8:2 or 7:3 or 1:9 or 15:85 or ethyl acetate-n-hexane, 4:6 or 3:1 hexane-ethyl acetate, 3:1 or 1:1 or 1:4 or cyclohexane-ethyl acetate, 1:1.

Thin layer chromatography is also useful. "Sephadex" is cross-linked dextran 2-(diethylamino) ethyl 2-[[2-(diethylamino)ethyl]diethylammonio]ethyl ether chloride hydrochloride epichlorhydrin (See Merck Index, Ninth Edition, item number 7337).

A solution of compound 7 (0.2 mol) and sodium iodide (0.3 mol) in acetone (150 ml.) is stirred at room temperature for 18 hours. The resulting suspension is cooled to about 0° C. and adjusted to about pH 7.2 by the addition of saturated aqueous sodium bicarbonate with stirring. After decolorizing by titration with 0.5 M aqueous sodium thiosulfate, water (150 ml.) is added dropwise to the stirred mixture to precipitate solid compound 8 which is collected by filtration, washed with acetone-water 1:1 (2×20 ml.), isopropanol (2×20 ml.) and ether (2×20 ml.) and dried.

Ampicillin is converted to compound 9 by the use of methyl acetoacetate in the procedures of U.S. Pat. No. 3,316,247. Then to a stirred solution of compound 9 (0.57 mol) in dimethylformamide (1 liter) there is added at 5° C. 0.5 mol of compound 8. After stirring for 15 minutes at 5° C. the reaction mixture is poured into an ice-cold mixture of ethyl acetate (4 liters) and saturated aqueous calcium chloride (2 liters) with stirring. The organic layer is separated, washed with saturated aqueous calcium chloride (2×500 ml.), filtered and evaporated to about one liter in vacuo to provide a concentrated solution of compound 10. To this concentrate there is added water (500 ml.) and n-butanol (500 ml.) and then, dropwise, 4 N hydrochloric acid with stirring until the amino-protecting group is removed to provide a solution of compound 11. After the addition of the acid is finished ether (1 liter) and water (500 ml.) are added to the stirred mixture, the aqueous phase is separated and the organic phase is extracted with water (800 ml.). The combined aqueous extracts are washed with ether (1 liter) and then sodium chloride (640 g.) and dichloromethane (2 liters) are added and the mixture is stirred for 15 minutes. The organic phase is separated and the aqueous phase is extracted with dichloromethane (1 liter) and the combined organic extracts are dried (MgSO₄) and evaporated to about 600 ml. under reduced pressure to give a concentrated solution of compound 11. Addition to the concentrate of 200 ml. 2-butanone followed by cooling precipitates solid 6-[(R)-2-Amino-2-phenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carbonyloxymethyl 2β-chloromethyl-2-α-methylpenam-3α-carboxylate sulfone (11) which is collected by filtration.

EXAMPLE 6 6-[(R)-2-Amino-2-p-hydroxyphenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carbonyloxymethyl 2β-chloromethyl-2-α-methylpenam-3α-carboxylate sulfone having the formula ##STR35## is produced by substituting amoxicillin for the ampicillin used in the procedure of Example 5. EXAMPLE 7 ##STR36##

As taught by U.S. Pat. No. 3,860,579, recrystallized phthalide (50 g., 0.375 mol) and recrystallized N-bromosuccinimide (0.375 mol) were refluxed by 4.5 hours in the presence of about 100 mgm α-azobutyronitrile in one liter CCl₄. The mixture was cooled to about 15° C. and filtered to remove succinimide which was itself washed with about 100 ml. CCl₄ and filtered. The combined CCl₄ phases were concentrated in vacuo to about 150 ml. giving solid 3-bromophthalide which was collected by filtration, washed with about 50 ml. CCl₄ and air-dried to yield 54 g. which weighed 50 g. after recrystallization from boiling cyclohexane, m.p. 84°-86° C. ##STR37##

To a stirred partial solution and partial suspension of compound 5 (BL-P2013; 2.3 g., 0.0075 mol) in 20 ml. dimethylformamide (DMF; dried at least 3 weeks over 3 A° molecular seives) was added 1.7 g. (0.008 mol) of 3-bromophthalide (12) and the mixture was stirred 4 hours at 22° C. The resulting mixture was poured into a mixture of 200 ml. ice-cold water and 200 ml. ice-cold ethyl acetate (rinsing the flask with a little ethyl acetate) and the mixture was shaken. Then the organic solvent phase was separated and washed with seven portions of ice-cold water (100 ml.). The ethyl acetate phase was washed once with saturated aqueous Na₂ SO₄, dried in the cold over Na₂ SO₄, filtered and evaporated to dryness in vacuo to leave as the residue an oil which was triturated twice with methylcyclohexane (25 ml.), twice with "Skellysolve B" (b.p. 60°-68° C., essentially n-hexane) (25 ml.) and four times with 25 ml. n-hexane to 2.5 g. compound 13 as a nearly white solid after drying in air. This product was then dried over P₂ O₅ at less than 1 mm Hg to give 2.5 g. compound 13, m.p. 104° C. (dec.). Its estimated purity was 85-95%.

Anal. Calcd. for C₁₆ H₁₄ ClNO₇ S: C, 51.61; H, 3.79; N, 3.77; Cl, 9.53. Found: C, 52.59; H, 4.67; N, 3.21; Cl, 7.73; K.F.H₂ O, 0.27.

EXAMPLE 8 Pivaloyloxymethyl 2β-Chloromethyl-2α-methylpenam-3α-carboxylate Sulfone

A mixture of 1 g. (0.0031 mole) of potassium 2β-chloromethyl-2α-methylpenam-3α-carboxylate sulfone hydrate and 1 g. of 3A molecular sieves was stirred in 15 ml. of dimethylacetamide for 2 hours at 23°. To this mixture was added 470 mg. (0.0031 mole) of pivaloyloxymethyl chloride and the stirring was continued for 18 hours. The molecular sieves were collected and the filtrate was diluted with 100 ml. of water and extracted with ethyl acetate. The ethyl acetate was washed nine times with water and dried over anhydrous magnesium sulfate. The solvent was removed at 30° (15 mm) to leave an oil which was chromatographed on silica using silicar CC-7 (methylene chloride 8, ethyl acetate 2) showing 1 spot Rf .5. The residue obtained crystallized from heptane ("Skellysolve B") to yield 100 mg. (M.P. 94°-95°) of pivaloyloxymethyl 2β-chloromethyl-2α-methylpenam-3α-carboxylate sulfone.

Anal. Calcd.: C, 44.03; H, 5.27; N, 3.67. Found: C, 44.20; H, 5.24; N, 3.63. The NMR and IR spectra were consistent for structure.

EXAMPLE 9 Sodium 2β-Chloromethyl-2α-methylpenam-3α-carboxylate Sulfone ##STR38##

To a stirred solution of 500 mg. of BL-P2013 (potassium salt) in 5 ml. of H₂ O and 10 ml. of ethyl acetate was added 2 N HCl until pH 1 was obtained (done in an ice-bath with vigorous stirring). The mixture was then saturated with Na₂ SO₄, the aqueous layer separated and the organic phase dried briefly in ice over Na₂ SO₄, filtered and treated dropwise with 50% NaEH (sodium 2-ethylhexanoate) in anhydrous n-butanol until neutral to moist pH paper. Product did not crystallize upon scratching and was then concentrated in vacuo to an oil which was dissolved in acetone (5 ml.), scratched--no crystals, ether added to cloud point--no cyrstals. Concentrated in vacuo on rotovap. to an oil which was dissolved in ethyl acetate--added one drop H₂ O--scratched--no crystals. Concentrated in vacuo and then residue was triturated with 5 ml. of n-butanol--200 mg. of amorphous white powder obtained, ether washed--air dried--vacuum dried over P₂ O₅ for 24 hours. 180 mg. final yield of sodium 2β-chloromethyl-2α-methylpenam-3α-carboxylate sulfone; dec. pt. >100° indef.

Anal. Calcd. for C₈ H₉ ClNO₅ SNa: C, 33.10; H, 3.13; N, 4.89: Found: C, 33.20; H, 3.69; N, 4.44 K.F.H₂ O, 4.04.

EXAMPLE 10 Potassium 2β-chloromethyl-2-methylpenam-3-carboxylate Sulfone (BL-P2013)

To 10 L of water, 130 g. (1.25 mole) of sodium hydrogen carbonate and 200 g. of 10% Pd on BaSO₄ were added 272 g. (0.565 mole) of p-nitrobenzyl 6α-bromo-2β-chloromethyl-2-methylpenam-3-carboxylate sulfone dissolved in 5 L of ethyl acetate. The mixture was hydrogenated at 40° C. and 1 Kg of pressure. After 5 hours, the hydrogen uptake became very slow and 200 g of 10% Pd on BaSO₄ were added and the mixture hydrogenated until no further significant hydrogen absorption was perceptible.

The slurry was filtered through a diatomaceous earth ("Celite") pad, the pad was washed with water and the aqueous phase washed with 3 L of ethyl acetate. To the aqueous solution, 3 L of ethyl acetate were added and the pH of the mixture adjusted to 1.5 with 150 ml of 12 N HCl at 10° C. The organic phase was separated and the aqueous solution saturated with Na₂ SO₄.10 H₂ O and extracted with 2×1 L of ethyl acetate. The combined extracts were dried with magnesium sulfate. The drying agent was removed and 260 ml of 2 N potassium 2-ethylhexanoic acid in butanol were added at 0° C.

After stirring 2 hours at 0° C., the potassium 2β-chloromethyl-2-methylpenam-3-carboxylate sulfone (BL-P2013) was collected and dried in a vacuum at room temperature.

Yield: 134.8 g (about 70%).

EXAMPLE 11 p-Nitrobenzyl 6α-Bromopenicillinate Sulfoxide ##STR39## Procedure

To 200 ml. of N,N-dimethylacetamide was added 44 g. (0.148 mole) of 6α-bromopenicillanic acid sulfoxide followed by 20.5 ml. (0.148 mole) of triethylamine and 38.2 g. (0.177 mole) of p-nitrobenzyl bromide. It was stirred at 22° for 20 hours.

The reaction mixture was poured into 1 liter H₂ O and extracted into 3×300 ml. of methylene chloride. The combined methylene chloride extracts were washed with 200 ml. of 5% aqueous sodium bicarbonate solution and dried over sodium sulfate at 5° for half an hour. The solution was filtered and evaporated under vacuum to a residue. The residue was diluted with ether and the solid collected by filtration to yield 54 g. p-nitrobenzyl 6α-bromopenicillinate sulfoxide after drying. 85% yield. nmr consistent for structure. The yield for this step was the same as for the K-salt esterification. The advantage is there was no need to make the K-salt. (A step which goes in 85% to 90% yield).

EXAMPLE 12 Preparation of p-Nitrobenzyl 6α-Bromopenicillanate Sulfoxide

To 4.375 L of N,N-dimethylacetamide was added 873.0 g (2.95 moles) of 6α-bromopenicillanic acid (S) sulfoxide and then with stirring and while keeping the internal temperature below 35° C., 293 g (2.95 moles) of triethylamine followed by 764 g (3.54 moles) of p-nitrobenzyl bromide. The mixture was stirred then at room temperature for 5 hours and let stand overnight.

The reaction mixture was poured into 20 L of water and extracted with 3×7 L of methylene chloride. The combined organic extracts were washed 5×7 L of water and then with 7 L of 5% aqueous sodium bicarbonate solution and dried over anhydrous magnesium sulfate.

The magnesium sulfate was filtered off and the solution evaporated to a crystalline residue; 4 L of diethyl ether were added and the crystals collected to yield after drying at room temperature 1171 g (92%) of p-nitrobenzyl 6α-bromopenicillanate sulfoxide.

Br 18.48% (calculated 18.53%), α_(D) (0.25% MeOH)+162°.

EXAMPLE 13 Preparation of p-Nitrobenzyl 6α-Bromo-2β-chloromethyl-2-methylpenam-3-carboxylate Sulfone

To 16 L of acetic acid was added 364.6 g (0.812 mole) of p-nitrobenzyl 6α-bromo-2β-chloromethyl-2-methylpenam-3-carboxylate. To the solution so obtained and stirred at room temperature, a solution of 282 g (1.78 mole) of KMnO₄ in 26 L of water was added dropwise over 3 hours. The mixture was then stirred at room temperature for 1 hour and H₂ O₂ (37%) was added dropwise until a colorless solution was obtained. 30 L of water were then added, the mixture stirred for 1 hour at room temperature and the crystalline precipitate was collected, washed with 3×5 L of water and with 2×2 L of ethanol and dried over vacuum at room temperature.

Yield: 297 g (76%)

α_(D) (0.5% CH₂ Cl₂)+75.9°

EXAMPLE 14 Preparation of BL-P2013 Free Acid ##STR40##

To a mixture of 25 ml of ethyl acetate and 10 ml of water was added 800 mg (0.00261 mole) of BL-P2013 potassium salt. After all of the solid had dissolved, the mixture was treated dropwise with 50% aqueous phosphoric acid with vigorous shaking until no more material precipitated from the aqueous layer. The ethyl acetate layer was separated, then washed with satuated sodium chloride solution and dried over anhydrous magnesium sulfate. The drying agent was removed by filtration and washed with 10 ml of ethyl acetate. (The wash solvent was combined with the original filtrate). "Skellysolve B" was then added to the ethyl acetate to the cloud point (approx. 10 ml). The mixture was treated with 500 mg of activated carbon ("Darko KB") and filtered. The filtrate was diluted with 15 ml of "Skellysolve B", then seeded with crystals of BL-P2013 free acid. After approx. 3 hours at room temperature, the crystalline precipitate of free acid was collected and dried in vacuo (15 min) over P.sub. 2 O₅ to obtain 323 mg (46%) m.p. slow decomp. over 100°.

Anal. Calcd. for C₈ H₁₀ ClNO₅ S: C, 35.89; H, 3.77; N, 5.23, Cl, 13.25: Found: C, 35.88, H, 3.91; N, 5.41; Cl, 13.52

This product was found to be unstable when stored at 23° C. for seven days.

EXAMPLE 15 6α-Bromopenicillanic Acid Sulfoxide ##STR41##

To 3 l of methylene chloride was added 300 g (0.75 mole) of 6α-bromopenicillanic acid N,N'-dibenzylethylenediamine salt and this suspension was cooled to 5°. Then over a 15 min. period, with good stirring, 130 ml of conc. HCl was added dropwise. The slurry was stirred at 5° for 2 hours. It was then filtered through a ("Celite") pad of diatomaceous earth and the cake was washed with 3×250 ml of methylene chloride.

The combined methylene chloride solutions were washed with 2×500 ml H₂ O and dried over sodium sulfate for 15 min. The sodium sulfate was removed by filtration and the filtrate evaporated under reduced pressure to approx. 750 ml.

This solution was cooled to 5° and, with vigorous stirring, 130 ml of 40% peracetic acid was added dropwise such that the temperature was maintained at 5° to 12°. The addition was quite exothermic. At the end of the addition, the slurry was stirred at 5° for 2 hours and the product collected by filtration and washed with 100 ml of cold H₂ O (5°) and 100 ml of cold methylene chloride (5°). There was obtained 126 g (57%) of 6α-bromopenicillanic acid sulfoxide, m.p. 129°. The ir and nmr spectra were consistent for the desired product.

Anal. Calcd. for C₈ H₁₀ BrNO₄ S: C, 32.44, H, 3.40; N, 4.73. Found: C, 32.30; H, 3.35; N, 4.71; H₂ O, 2.18.

Potassium 6α-Bromopenicillanate Sulfoxide ##STR42##

To 3 l of acetone was added 126 g (0.43 mole) of 6α-bromopenicillanic acid sulfoxide and 162 ml of 50% by weight potassium 2-ethylhexanoic acid in n-butanol. After stirring 1 hour at 22°, the product was collected by filtration, washed with 2×250 ml of acetone and dried. There was obtained 127 g (90%) of potassium 6α-bromopenicillanate sulfoxide, m.p. 185°. The ir and nmr spectra were consistent for the desired structure.

Anal. Calcd. for C₈ H₉ BrKNO₄ S: C, 28.75; H, 2.71; N, 4.19. Found: C, 29.03; H, 2.78; N, 4.04.

p-Nitrobenzyl 6α-Bromopenicillanate Sulfoxide ##STR43##

To 1 l of N,N-dimethylacetamide was added 145 g (0.43 mole) potassium 6α-bromopenicillanate sulfoxide, and, with stirring, there was then added 115 g (0.53 mole) of p-nitrobenzyl bromide at 22°. The mixture was stirred at 22° for 20 hours.

The reaction mixture was poured into 3 l of H₂ O and extracted with 3×1500 ml of ethyl acetate. The combined ethyl acetate extracts were washed with 2×500 ml of 5% aqueous sodium bicarbonate solution and dried over sodium sulfate for 1/2 hour. The sodium sulfate was filtered off and the filtrate evaporated under reduced pressure to a residue to which 1 l of of diethyl ether was added causing the product of crystallize. The crystals were collected by filtration, washed with 2×100 ml of diethyl ether and dried to yeild 162 g (87%) of p-nitrobenzyl 6α-bromopenicillanate sulfoxide, m.p. 111°. The ir and nmr spectra were consistent for the desired structure.

Anal. Calcd. for C₁₅ H₁₆ BrN₂ O₆ S: C, 41.78; H, 3.51; N, 6.50. Found: C, 41.66; H, 3.45; N, 6.85; H₂ O, 0.69.

p-Nitrobenzyl 6α-Bromo-2β-chloromethyl-2-methylphenam-3-carboxylate ##STR44##

To 1 l of p-dioxane was added to 70 g (0.16 mole) of p-nitrobenzyl 6α-bromopenicillanate sulfoxide followed by 21.2 ml (0.10 mole) of benzoyl chloride and 21.8 ml (0.19 mole) of quinoline. The reaction mixture was refluxed for 4 hours and then cooled to 22°, poured into 2500 ml of H₂ O and extracted into 3×800 ml of ethyl acetate. The combined ethyl acetate extracts were washed with 300 ml of 5% aqueous sodium bicarbonate solution, 300 ml of 5% aqueous phosphoric acid and 300 ml of H₂ O. The ethyl acetate solution was dried over sodium sulfate for 1/2 hour and the sodium sulfate was removed by filtration. The filtrate was evaporated under reduced pressure to a residue which was redissolved in 1 l. of ethyl acetate and again evaporated under reduced pressure to a residue. The 1 l. of diethyl ether was added and the product collected by filtration to yield 41 g (57%) of p-nitrobenzyl 6α-bromo-2β-chloromethyl-2-methylpenam-3-carboxylate, m.p. 132°. The ir and nmr spectra were consistent for the desired structure.

Anal. Calcd. for C₁₅ H₁₄ BrClN₂ O₅ S: C, 40.06; H, 3.14; N, 6.23. Found: C, 40.62; H, 3.11; N, 6.13.

p-Nitrobenzyl 6α-Bromo-2β-chloromethyl-2-methylpenam-3-carboxylate Sulfoxide ##STR45##

To 1200 ml of methylene chloride was added 51 g (0.11 mole) of p-nitrobenzyl 6α-bromo-2β-chloromethyl-2-methylpenam-3-carboxylate followed by 23 g (0.12 mole) of m-chloroperoxybenzoic acid. The solution was stirred at 22° for 2 hours and evaporated under reduced pressure to a wet residue. The residue was stirred with 4 l of diethyl ether for 1 hour and allowed to stand at 10° for 20 hours. The product crystallized out and was collected by filtration, washed with 2×200 ml of diethyl ether and dried, yielding 39 g p-nitrobenzyl 6α-bromo-2β-chloromethyl-2-methylpenam-3-carboxylate sulfoxide (75%), m.p. 132°. The ir and nmr spectra were consistent for the desired structure.

Anal. Calcd. for C₁₅ H₁₄ BrClN₂ O₆ S: C, 38.69; H, 3.03; N, 6.07. Found: C, 38.98; H, 3.04; N, 5.84; H₂ O, 0.35.

Potassium 2β-Chloromethyl-2-methylpenam-3-carboxylate Sulfone (BL-P2013) ##STR46##

To 600 ml of H₂ O was added 8 g of 30% Pd on "Celite" and 16 g (0.19 mole) of sodium bicarbonate. Then 32 g (0.69 mole) of p-nitrobenzyl 6α-bromo-2β-chloromethyl-2-methylpenam-3-carboxylate sulfoxide was dissolved in 400 ml of ethyl acetate and added to the aqueous slurry. The mixture was hydrogenated on a Paar apparatus at 50 p.s.i. at 22° for 4 hours. The slurry was filtered through a thin "Celite" pad on a sintered glass funnel, the pad was washed with 2×50 ml H₂ O and the aqueous layer of the combined filtrate and washings was separated. The aqueous layer was washed with 200 ml of diethyl ether, then was cooled to 5° and, with stirring, a solution of 12 g. (0.076 mole) of KMnO₄ in 200 ml of H₂ O was added dropwise over a 1/2 hour period, keeping the pH between 7.5 and 8.0 by the addition of 40% of H₃ PO₄. When the pink color persisted for 5 minutes, no more KMnO₄ solution was added. The reaction mixture was stirred with a small amount (approx. 50 mg) of sodium bisulfite for 1/2 hour, and then the slurry was filtered through a "Celite" pad. The pad was washed with 2×50 ml of H₂ O. The combined filtrate and washings were layered with 500 ml of ethyl acetate and, with stirring, the pH was adjusted to 1.5 by the addition of 2 N HCl. The layers were separated and the aqueous layer was saturated with sodium sulfate. It was reextracted with 2×400 ml of ethyl acetate and the combined ethyl acetate extracts were dried over sodium sulfate for 1/2 hour at 5°. The sodium sulfate was removed by filtration and the filtrate evaporated under reduced pressure to a residue. That residue was dissolved in 160 ml of acetone and 160 ml of diethyl ether and 50% by weight of potassium 2-ethylhexanoate in n-butanol was added until the solution was neutral to moist pH paper. The potassium salt of BL-P2013 crystallized out, was collected by filtration, washed with diethyl ether and dried. Yield 16 g potassium 2β-chloromethyl-2-methylpenam-3-carboxylate sulfone (BL-P2013) (76%), m.p. 202°. The ir and nmr spectra were consistent for the desired structure.

Anal. Calcd. for C₈ H₉ ClKNO₅ S: C, 31.42; H, 2.97; N, 4.58. Found: C, 31.18; H, 2.98; N, 4.51; H₂ O, 0.93.

EXAMPLE 16 Pivaloyloxymethyl 2β-Chloromethyl-2-methylpenam-3-carboxylate Sulfone (BL-P2024) ##STR47##

To a stirred suspension of 14.6 g (0.0487 mole) of potassium 2β-chloromethyl-2-methylpenam-3-carboxylate sulfone (BL-P2013) in 200 ml of acetone was added 4 ml of a 10% aqueous solution of sodium iodide and the mixture was brought to reflux on the steam bath. To this refluxing suspension was added 14.8 ml. (0.1 mole) of redistilled chloromethyl pivalate (bp 34° C. at 7 mm Hg) and all at once. The mixture was stirred at reflux for three hours and then cooled to room temperature (22° C.). The crystalline solids were collected by filtration, washed with 3×30 ml of acetone and the combined filtrates were evaporated to an oil under reduced pressure at <22° C. The oil was then taken up in 500 ml of ethyl acetate and washed once with water (200 ml) and once with saturated Na₂ SO₄ solution (200 ml). The solution was then dried briefly over Na₂ SO₄ while being stirred with 2 g of decolorizing carbon with cooling (ice bath). After 20 min. the mixture was filtered through a "Celite" pad and the pad washed with 4×100 ml of ethyl acetate. The combined filtrates were concentrated under reduced pressure at 22° C. to an oil. The oil was then further concentrated at about 22° C. and <1 mm Hg to remove most of the residual chloromethyl pivalate. The remaining oil was then triturated twice with 50 ml portions of n-pentane and then left over the weekend at about 10° C. under n-pentane. The resulting solid crystalline mass was then broken up to a powder under 40 ml of a 4:1 mixture of diethyl ether-n-pentane. The product was then collected by filtration, washed with diethyl ether-n-pentane (1:1) then n-pentane and air dried. After drying under high vacuum for four hours over P₂ O₅ there was obtained 13.37 g pivaloyloxymethyl 2β-chloromethyl-2-methylpenam-3-carboxylate sulfone (BL-P2024) about (75%), m.p. 93°-95° C.

Purification of BL-P2024

Approximately 3 g. of crude BL-P2024 (obtained as described above) was dissolved in 5 ml. of ethyl acetate, placed on a 4.5×40 cm. column of silica gel (Mallinckrodt CC-7), and eluted with 4:1 v/v CH₂ Cl₂ -ethyl acetate. The fractions containing a single spot at R_(f) 0.84 (TLC on silica gel plates with 4:1 CH₂ Cl₂ -ethyl acetate, I₂ detection) were combined and concentrated under reduced pressure to 1.38 g. of a crystalline solid. A portion of this material (900 mg.) was dissolved in 5 ml. of ethyl acetate; the resulting solution was filtered, diluted almost to the cloud point with petroleum ether ("Skellysolve B") and then stored at room temperature for three days. The crystals which formed were collected by filtration, washed with petroleum ether and dried to give 560 mg., m.p. 100°-101°., of purified BL-P2024.

Anal. Calcd. for C₁₄ H₂₀ ClNO₇ S: C, 44.03; H, 5.27; N, 3.67: Found: C, 44.11; H, 5.08; N, 3.85.

All temperatures in this application are given in degrees Centigrade.

EXAMPLE 17 Preparation of BL-P2013 Ammonium Salt

1. The free acid of BL-P2013 (250 mg.) dissolved in 20 ml. of acetone-methanol (1:1 by volume) was filtered to get a clear solution.

2. Anhydrous ammonium solution was prepared by adding 1 ml. of ammonium hydroxide (30% reagent grade) to 10 ml. of acetone-methanol (1:1 by volume) solvent and then 1 gm. of anhydrous magnesium sulfate was added to that solution with mild agitation and the mixture was filtered through a filter paper; the filtrate was designated "anhydrous ammonium solution."

3. To the filtrate of Procedure 1, approximately 2 ml. of "anhydrous ammonium solution" was gradually added and mixed well.

4. A 100 ml. portion of diethyl ether was mixed with the mixture from Procedure 3 to precipitate the ammonium salt of BL-P2013.

5. The white ammonium salt was isolated from the solvent and washed with 2 portions of 50 ml. each of diethyl ether.

6. The isolated powder was dried at 35° C. vacuum oven for overnight.

7. Analytical data were as follows: Calculated % C 33.7; H 4.6; N 9.8; Found C 33.66; H 4.63; N 10.12; dry by KF

Microscopic Examination: crystalline substance.

EXAMPLE 18 Preparation of Non-hygroscopic Sodium Salt of BL-P2013

1. Dissolve 50 mg. of the free acid of BL-P2013 in 4 ml. of acetone-methanol (1:1 by volume) mixture. Filter to get a clear solution.

2. Prepare sodium 2-ethylhexanoate solution by dissolving 40 mg. of sodium 2-ethylhexanoate in 10 ml. of acetone-methanol (1:1 by volume) mixture.

3. To the filtrate of Procedure 1, add the 10 ml. solution of Procedure 2 and mix well.

4. A 10 ml. portion of diethyl ether was mixed with the mixture from Procedure 3 to precipitate the sodium salt of BL-P2013.

5. The white salt was immersed in the diethyl ether for 1-2 hours and then was isolated from the solvent and washed with 3 portions of 5 ml. each of diethyl ether.

6. The isolated powder was dried at 30° C. vacuum oven for overnight.

EXAMPLE 19 Recrystallization of BL-P2013 ##STR48## BL-P2013 (400 mg.) was dissolved in a minimum amount of acetone-H₂ O (1:1) by volume and diluted with 10 ml. of acetone, filtered, then diluted with acetone to about 25 ml., scratched, and after 30 minutes the crystalline hydrate was collected by filtration, washed well with acetone, air dried and then vacuum dried at <1 mm. Hg overnight.

Yield 280 mg.

Anal. Calcd. for C₈ H₉ ClNOSK.H₂ O: C, 29.67; H, 3.39; N, 4.63; Cl, 10.94; H₂ O, 5.55. Found: C, 29.32; H, 3.32; N, 4.44; Cl, 11.31; H₂ O, 5.90.

EXAMPLE 20 N,N'-Dibenzylethylenediamine Salt of BL-P2013

BL-P2013+1/2 N,N'-Dibenzylethylenediamine diacetate ##STR49##

306 mg. (0.001 ml) of BL-P2013 was dissolved in 7 ml. H₂ O and added to a solution of 180 mg. (0.0005 mol) of N,N'-dibenzylethylenediamine diacetate in 7 ml. H₂ O. The mixture was stirred and the salt crystallized and after stirring approximately 10-15 minutes the salt was collected by filtration and air dried to yield N,N'-dibenzylethylenediamine salt of BL-P2013 (300 mg). The material was recrystallized by dissolving it in approximately 10 ml. of boiling acetone and diluting with ether to the cloud point. 260 mg. of air dried and vacuum dried material was obtained.

Anal. Calcd: C, 51.69; H, 5.42; N, 7.53; Cl, 9.55. Found: C, 49.39; H, 5.49; N, 7.05; Cl, 8.96; H₂ O, 1.23 (KF).

EXAMPLE 21 Chloromethyl Ester of BL-P2013 ##STR50##

To a vigorously stirred mixture of 15.25 g (0.05 mol) of BL-P2013 (5), 15 g. (0.15 mol) KHCO₃ and 1.7 g (0.005 mol) of tetrabutylammonium hydrogen sulfate (Aldrich Chem. Co.) in a mixture of 50 ml. water and 50 ml. CH₂ Cl₂ there was added dropwise a solution of 9.5 g (0.0575 mol) of ClCH₂ -O-SO₂ Cl in 40 ml. CH₂ Cl₂. The temperature rose to 26° C. and after the addition (which took about 15 minutes) the mixture was stirred another 30 minutes. Because the product crystallized out more CH₂ Cl₂ (about 400 ml.) was added to obtain a solution. The separated CH₂ Cl₂ layer and a 50 ml. CH₂ Cl₂ wash were combined, dried over MgSO₄ with stirring and 2 g of decolorizing carbon ("Darco KB") was added. After about 30 minutes the mixture was filtered, concentrated to about 50 ml. and isopropyl alcohol (150 ml.) was added. The rest of the CH₂ Cl₂ was then removed under reduced pressure. The resulting crystalline precipitate was collected by filtration, washed well with isopropyl alcohol and air-dried. After vacuum drying at less than 1 mm. Hg there was obtained 8.5 g of chloromethyl 2β-chloromethyl-2-methylpenam-3-carboxylate sulfone (7). M.p. 116° (dec., darkens above 100° C.).

Anal. Calcd. for C₉ H₁₁ Cl₂ NO₅ S: C, 34.18; H, 3.51; N, 4.43; Cl, 22.43. Found: C, 34.16; H, 3.45; N, 4.47; Cl, 22.46; H₂ O, 0.33 (KF).

Estimated purity in the 90-95% range.

Iodomethyl Ester of BL-P2013 ##STR51##

To a stirred mixture of 5 g. (0.0159 mol) of the chloromethyl ester of BL-P2013 (7) in 25 ml. acetone was added 3 g. (0.02 mol) of sodium iodide. The resulting slurry was stirred for 17 hours and then cooled to about 0° C. Two drops of saturated aqueous KHCO₃ were added and the mixture was slowly diluted dropwise with water over ten minutes until 50 ml. had been added. The slurry underwent a sudden color change from yellow to grey to purple to black and therefore the crystals were immediately collected by filtration and washed with cold acetone-water (1:2) and then isopropyl alcohol (3×10 ml), then diethyl ether and finally n-pentane and air-dried to yield 5.55 g. (91% yield) of the iodomethyl ester of BL-P2013 (8). M.p. 118°-119° C. with decomposition. Purity estimated at about 90%.

6-[(R)-2-Amino-2-phenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[ 3.2.0]heptane-2-carbonyloxymethyl 2β-chloromethyl-2-α-methylpenam-3α-carboxylate sulfone (11) ##STR52##

To a stirred mixture cooled in an ice-bath of 5.46 g. (0.01 mol) of the indicated Dane salt of ampicillin 9 (which was solvated with one molecule of isopropyl alcohol) in 60 ml. acetone there was added 4.08 g. (0.01 ml) of the iodomethyl ester of BL-P2013 (8) and the resulting nearly clear solution was stirred for five hours with the ice-bath removed after 30 minutes. Then most of the acetone was removed in vacuum on the roto-vap and the resulting concentrated solution was dissolved in 200 ml. cold ethyl acetate which was then washed with 2×50 ml. ice cold water and 2×100 ml. saturated aqueous Na₂ SO₄. The ethyl acetate solution was then dried over Na₂ SO₄, filtered and most of the ethyl acetate was removed in vacuo on the roto-vap. The residue was triturated with 2×200 ml. dry diethyl ether and the resulting solids were collected by filtration to give 5.5 g. of 10 as a pinkish powder. This powder was stirred in a mixture of 50 ml. water, 50 ml. n-butanol and 20 ml. ethyl acetate while 6 N HCl was added dropwise to pH 2.5. Then occasionally a drop or two of HCl was added to keep the pH at 2.2-2.5 over 45 minutes. When the pH no longer drifted upward there was added to this mixture 100 ml. diethyl ether with good stirring. The aqueous phase was separated and combined with a second 25 ml. H₂ O extract of the organic layer. The aqueous solution was extracted once with 50 ml. diethyl ether and the ether was discarded.

The aqueous layer was then stirred vigorously under a layer of 100 ml. 2-butanone (methyl ethyl ketone) while Na₂ SO₄ was added to saturate the aqueous layer. The 2-butanone layer was separated, dried over Na₂ SO₄ for 30 minutes in an ice-bath, filtered and concentrated in vacuo to near dryness. The residual oil was triturated to a solid with n-butanol, washed well with ether, then n-pentane, air-dried and then vacuum-dried over P₂ O₅ at <1 mm Hg pressure to yield 1.6 g. 6-[(R)-2-amino-2-phenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carbonylmethyl 2β-chloromethyl-2-α-methylpenam-3α-carboxylate sulfone (11) in crude form. The IR and nmr spectra were consistent with structure 11 but not with high purity. This solid product was estimated to contain at least 40% and perhaps as much as 80% 6-[(R)-2-amino-2-phenylacetamido]3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[ 3.2.0]heptane-2-carbonyloxymethyl 2β-chloromethyl-2-α-methylpenam-3α-carboxylate sulfone.

EXAMPLE 22 Improved Synthesis of BL-P2013

This procedure simplifies production of BL-P2013 by eliminating the previous use of catalytic reduction. ##STR53## (See page 633 of Cephalosporins and Penicillins, edited by Edwin H. Flynn, Academic Press, New York, 1972)

6α-Bromopenicillanic acid sulfoxide (1) (30 g., 0.1 mol) was dissolved in 1 l. dry CH₂ Cl₂ followed by the addition of 16.2 ml. (0.2 mol) pyridine and 29.8 g. (0.2 mol) trichloroethanol. Then 20 g. (0.1 mol) of dicyclohexylcarbodiimide was added and the mixture was stirred at 22° for 16 hours. Dicyclohexylurea began to precipitate out; at the end it was removed by filtration. The filtrate was washed with 200 ml. of 5% aqueous sodium bicarbonate, 200 ml. of 10% phosphoric acid and 100 ml. of saturated aqueous sodium sulfate. The organic phase was dried over sodium sulfate at 5° C. for 30 minutes, filtered and evaporated to an oil. Diethyl ether was added and, with scratching, the product 2 crystallized out (27 g., 63% yield). ##STR54##

Compound 2 (26.5 g., 0.062 mol) was dissolved in 500 ml. p-dioxane and there was added 8.5 ml. (0.078 mole) benzoyl chloride and 8.75 ml. (0.078 mole) quinoline. The solution was refluxed for four hours and then poured into 1100 ml. water and the product 3 was extracted into 2×400 ml. ethyl acetate. The ethyl acetate extracts were combined, successively washed with 200 ml. 5% aqueous sodium bicarbonate, 200 ml. 5% phosphoric acid and 200 ml. saturated aqueous sodium sulfate, dried over sodium sulfate at 5° C. for thirty minutes and evaporated to an oil (3) which was used "as is" for the next reaction. ##STR55##

Compound 3 obtained in the previous step was dissolved in 1 l. glacial acetic acid and, with stirring at 22° C., a saturated aqueous solution of KMnO₄ was added dropwise until a pink color persisted (that is, a drop placed on a piece of filter paper gave a pink coloration). Then with cooling 30% H₂ O₂ was added dropwise until a clear solution was obtained; some white precipitate was present. The solution was poured into 2.5 l. water and the product 4 was extracted into 3×500 ml. ethyl acetate. The ethyl acetate was washed with 5% aqueous sodium bicarbonate until neutral (that is, no more bubbling upon addition), dried over sodium sulfate and evaporated to leave 4 as the residue. It was left at 10° C. for one day and then triturated with "Skellysolve B" to yield 9.1 g. solid 4. The yield was 28% of theory for steps 2 and 3 combined. ##STR56## (See U.S. Pat. No. 4,164,497)

Zinc dust (3.75 g.) was slurried in 5 ml. glacial acetic acid and cooled to 5° C. To this mixture there was added a solution of 4 (3 g.; 0.0057 mole) in 15 ml dimethylformamide and the resulting slurry was stirred at 5° for 2.5 hours.

The zinc was then filtered off and the pale yellow solution was poured into 80 ml. of 5% aqueous hydrochloric acid. That mixture was extracted with 3×25 ml. ethyl acetate. The combined ethyl acetate extracts were extracted with 3×20 ml. of 5% aqueous sodium bicarbonate, saving the ethyl acetate phase after separation.

The bicarbonate extracts were combined, placed under a layer of ethyl acetate, adjusted to pH 1.5 by the addition of 2 N HCl and saturated with sodium sulfate. The ethyl acetate was separated and the aqueous phase was extracted with 2×30 ml. ethyl acetate.

All of the ethyl acetate phases above were combined, dried over sodium sulfate and evaporated to an oil (which was the free acid form of BL-P2013) which was dissolved in about 20 ml. acetone to which 20 ml. diethyl ether was then added. Then 50% potassium 2-ethylhexanoate (KEH) in dry n-butanol was added to neutrality. The product 5 (BL-P2013) crystallized out. After stirring 0.5 hour at 22° it was collected by filtration to yield 650 mgm. of 5 (37% yield).

A 50 mgm. sample of 5 was dissolved in 0.5 ml. water and 20 mgm. N,N'-dibenzylethylenediamine (DBED) diacetate was added. The DBED salt of 5 crystallized out, was collected by filtration, washed with water and dried over P₂ O₅ under vacuum to yield N,N'-dibenzylethylenediamine 2β-chloromethyl-2-methylpenam-3-carboxylate sulfone (DBED salt of free acid 5).

Another sample of 5 (450 mgm.) was dissolved in 3 ml. water to which was added a solution of 270 mgm. DBED diacetate in 2 ml. H₂ O. With scratching the DBED salt of 5 crystallized out (430 mgm.). Recrystallization from about 5 ml. boiling acetone yielded 270 mgm.

EXAMPLE 23 6-[(R)-2-Amino-2-p-hydroxyphenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carbonyloxymethyl 2β-chloromethyl-2-α-methylpenam-3α-carboxylate sulfone having the formula ##STR57## is produced by substituting the corresponding Dane salt of amoxicillin for the ampicillin used in the procedure of Example 21. BIOLOGICAL DATA

The product of Example 1, Compound 5, having the structure ##STR58## will be referred to below as BL-P2013.

Although at best a very weak antibacterial agent itself, BL-P2013 inhibits β-lactamases and protected ceforanide and amoxicillin from destruction by β-lactamase-producing bacteria in vitro and in vivo when used in combination with those two agents.

                  TABLE 1                                                          ______________________________________                                         Antibacterial Activity of the New Sulfone                                                       MIC (mcg/ml)                                                  Organism           BL-P2013  Ampicillin                                        ______________________________________                                         S. pneumoniae                                                                               A-9585      16      0.004                                         S. pyogenes  A-9604      63      0.004                                         S. aureus    A-9537    >125      0.16                                          S. aureus +                                                                    50% serum    A-9537    >125      0.06                                          S. aureus Pen-                                                                 Res          A-9606    >125      >125                                          S. aureus Meth-                                                                Res          A15097    >125      125                                           S. faecalis  A20688    >125      0.13                                          E. coli      A15119    >125      1                                             E. coli      A20341-1  >125      >125                                          K. pneumoniae                                                                               A15130    >125      125                                           K. pneumoniae                                                                               A20468    >125      >125                                          P. mirabilis A-9900    >125      0.13                                          P. vulgaris  A21559    >125      125                                           P. morganii  A15153    >125      >125                                          P. rettgeri  A21203    >125      4                                             S. marcescens                                                                               A20019    >125      16                                            E. cloacae   A-9659    >125      63                                            E. cloacae   A-9656    >125      >125                                          P. aeruginosa                                                                               A-9843A   >125      >125                                          P. aeruginosa                                                                               A21213    >125      >125                                          ______________________________________                                    

                  TABLE 2                                                          ______________________________________                                         Anti-Bacteroides Activity of Ceforanide and Amoxicillin                        Alone and in Combination with BL-P2013                                                  MIC (mcg/ml)*                                                                                Cefor-       Amoxi-                                                            anide        cillin                                            Beta-           +BL-P        +BL-P                                             lact-   Cefo-   2013   BL-P  2013   Amoxi-                              Organism                                                                              amase   ranide  (1:1)  2013  (1:1)  cillin                              ______________________________________                                         B. fragilis                                                                    A21916 +       63       --2   >125   --2   8                                   A22053 +       32       --4   63     --2   8                                   A22021 +       32       --2   32     ---2  4                                   A21875 +       32       --4   63     --2   8                                   A22534 +       >125     --32  125    --16  >125                                A22697 +       63       --8   63     --2   8                                   A22693 +       63       --4   63     --2   16                                  A22694 +       125      --16  63     --2   16                                  A22695 +       >125     ---16 32     --4   125                                 A22696 +       >125     ---32 63     --8   >125                                A22533 +       >125     ---32 32    32     >125                                A22535 +       >125     --32  125    --32  >125                                A22792 +       >125     --8   32     --4   125                                 A22793 +       32       --4   32     --2   8                                   A22794 +       32       --4   32     --2   8                                   A22795 +       63       --4   32     --4   16                                  A22797 +       63       --4   63     --2   16                                  A22798 +       32       --4   63     --2   8                                   B. theta-                                                                      iotaomic-                                                                      ron                                                                            A22277 +       125      --4   63     --2   16                                  A22279 +       125      --8   63     --4   16                                  Bac-                                                                           teroides                                                                       species                                                                        A20934 +       32       --4   32     --2   8                                   A21959 +       63       --4   32     --2   16                                  A20929 +       63       --4   32     --2   16                                  A21954 +       63       --16  63     --2   16                                  A20933 +       63       --16  63     ---4  8                                   A20930 +       125      --8   125    --4   32                                  A20931 +       63       --4   32     --2   16                                  A20927-1                                                                              -       0.5     1      63    0.13   0.13                                A20935 -       2       2      125   0.13   0.13                                ______________________________________                                          -- good synergism -- marginal synergism                                        *Minimum inhibitory concentration (MIC) determined by the agar dilution        method using 50X dilutions of 24 hour cultures as inocula dispensed by th      Steer's inoculator. Assay medium composed of Brucella Agar plus 5% laked       sheep blood and 10 mcg/ml vitamin K.                                     

                  TABLE 3                                                          ______________________________________                                         Therapeutic Efficacy of Amoxicillin in Combination with                        BL-P2013 in Mice Experimentally Infected with a Beta-                          Lactamase Strain of Staphylococcus aureus                                      Challenge   PD.sub.50 /Treatment (mg/kg)                                       Organ-                                                                               (No. of   Amoxicillin (A)                                                                            BL-P2013 (B)                                                                            A+B (1:1)                                 ism   Organisms)                                                                               IM      PO    IM   PO    IM   PO                               ______________________________________                                         S.    5 × 10.sup.8                                                                       >800    >800  >50  >200  6.3  44                               aureus                                                                               5 × 10.sup.8                                                                       >800    >800  >50  >200  19   77                               A-9606                                                                               7 × 10.sup.8                                                                       >800    --    >50  --    9.6  --                               ______________________________________                                          Treatment schedule: Drugs administered 0 and 2 hours postinfection.      

                                      TABLE 4                                      __________________________________________________________________________     Blood levels of BL-P2013 and its Pivaloyloxymethyl Ester                       (BL-P2024) After Oral Administration to Mice                                               Blood Level (μg/ml)                                                                              Half-                                                Dose 15 30  60                                                                               90  120 150 life                                                                               Assay                                     Compound                                                                              (mg/kg)                                                                             Minutes After Adiminstration                                                                        (min.)                                                                             Organism                                  __________________________________________________________________________     BL-P2013                                                                              100  4.5                                                                               5.1 3.9                                                                              2.3 1.5 0.8 50  E. coli                                                                        A-9675                                           100  4.6                                                                               4.1 3 <2.6                                                                               <2.6                                                                               <2.6                                                                               --  S. aureus                                                                      A-9606                                           200  7.4                                                                               9.8 7.1                                                                              4.1 2.8 <2.6                                                                               50  S. aureus                                                                      A-9606                                    BL-P2024                                                                              100  12.8                                                                              12.9                                                                               9.7                                                                              7.2 5.5 4.2 70  E. coli                                                                        A-9675                                           100  13.1                                                                              12  8 5.7 3.8 <2.5                                                                               60  S. aureus                                                                      A-9606                                           200  14.7                                                                              14.4                                                                               9.8                                                                              8.7 5.1 >2.5                                                                               60  S. aureus                                                                      A-9606                                    __________________________________________________________________________      Values represent averages of two to four tests.                          

                  TABLE 5                                                          ______________________________________                                         Blood Levels and Half-Life of BL-P2024 After Oral                              Administration of Various Doses to Mice                                                   Blood Level (μg/ml)                                              Dose         15     30     60  90  120  150  t 1/2                             Compound                                                                               (mg/kg)  Minutes After Administration                                                                       (min.)                                    ______________________________________                                                  25      5.9    6.2  3.6 1.9 1.3  0.7  40                              BL-P2024                                                                                50      7.7    9.5  6.3 4.7 3.5  2.3  60                                      100      12.3   12.2 9.4 7.2 5.7  4.6  85                                      200      14.7   14.4 9.8 8.7 5.1  <2.5 60                              ______________________________________                                          BL-P2024 was suspended in TweenCMC-water.                                      Values are averages of 2 experiments for 25 and 50 mg/kg doses, 5 to 6         experiments for the 100 mg/kg dose, and 2 to 3 experiments for the 200         mg/kg dose.                                                                    Assay organism:                                                                E. coli A9675 for all doses except for 200 mg/kg of BLP2024                    (S. aureus A9606).                                                       

                                      TABLE 6                                      __________________________________________________________________________     Therapeutic Efficacy of Amoxicillin in Combination with BL-P2013 in Mice       Experimentally Infected with β-Lactomase Producing Strains of S.          aureus and E. coli                                                             Challenge  PD.sub.50 /Treatment (mg/kg)                                        (No. of    Amoxicillin:BL-P2013        BL-P                                    Organism                                                                            Organisms)                                                                           Amoxicillin                                                                           4:1  2:1 1:1 1:2 1:4 2013                                    __________________________________________________________________________     S. aureus                                                                           7 × 10.sup.8                                                                   >200  >200:>50                                                                             44:22                                                                              33:33                                                                              38:76                                                                               25:100                                                                            >200                                    A9606                                                                               2 × 10.sup.9                                                                   >800        33:17                                                                              14:14                                                                              10:20   >200                                    S. aureus                                                                           4 × 10.sup.8                                                                   >200  132:66                                                                               78:39                                                                              44:44       >200                                    A15091                                                                              5 × 10.sup.8                                                                   >800        114:57                                                                             100:100                                                                             66:132 >200                                    S. aureus                                                                           6 × 10.sup.8                                                                   >200  174:44                                                                               44:22                                                                              25:25                                                                              22:44                                                                              19:76                                                                               174                                    A20379                                                                              5 × 10.sup.8                                                                   >200        50:25                                                                              43:43                                                                              35:70   >200                                    E. coli                                                                             5 × 10.sup.5                                                                   >200   25:6.3                                                                               11:5.5                                                                            11:11       >200                                    A20649                                                                              6 × 10.sup.5                                                                   >200   20:5 8:4 6:6 10:20                                                                              63:25                                                                              >200                                    E. coli                                                                             7 × 10.sup.5                                                                   >200   6:1.5                                                                               6:3 5:5         >200                                    A21223                                                                              6 × 10.sup.5                                                                   >200   8:2  6:3 6:6 4:8 3.5:14                                                                             >200                                         7 × 10.sup.5                                                                   >200          7:3.5         >200                                    E. coli                                                                             8 × 10.sup.5                                                                   >200   8:2  6:3 3:3 4:8  4:16                                                                              >200                                    A9675                                                                               7 × 10.sup.5                                                                   >100   10:2.5                                                                              6:3 7:7 2.5:5   >100                                         6 × 10.sup.5                                                                   >400   13:3.3                                                                              6:3 5:5  5:10   >200                                    __________________________________________________________________________      Treatment schedule:                                                            Drugs were administered orally at 0 and 2 hours postinfection.                 Drugs were suspended in TCMC.                                            

                                      TABLE 7                                      __________________________________________________________________________     Therapeutic Efficacy of Amoxicillin in Various Combinations with the           Pivaloyloxymethyl Ester (Bl-P2024) of                                          BL-P2013 in Mice Experimentally Infected                                       with β-Lactamase Producing Strains of S. aureus and E. coli               Challenge       PD.sub.50 /Treatment (mg/kg).sup.a                             (No. of    Drug-                                                                               Amoxi-                                                                             Amoxicillin: BL-P2024                                                                     BL-P                                            Organism                                                                            Organisms)                                                                           Vehicle.sup.b                                                                       cillin                                                                             4:1 2:1 1:1                                                                               2024                                            __________________________________________________________________________     S. aureus                                                                           5 × 10.sup.8                                                                   TCMC >800    66:33                                                                              57:57                                                                             >200                                            A15091                                                                         S. aureus                                                                           5 × 10.sup.8                                                                   TCMC >800    12:6                                                                               9:9                                                                                200                                            A20379                                                                         E. coli                                                                             9 × 10.sup.5                                                                   50%  >100                                                                               12:12                                                                              6:3 3:3                                                                               >25                                             A9675      DMSO                                                                E. coli                                                                             7 × 10.sup.5                                                                   50%  >100                                                                                10:2.5                                                                              7:3.5                                                                            4:4                                                                               >25                                             A9675      DMSO                                                                E. coli                                                                             7 × 10.sup.5                                                                   TCMC >100                                                                               8:2 6:3 5:5                                                                               >25                                             A9675                                                                          E. coli                                                                             6 × 10.sup.5                                                                   TCMC >400                                                                               9.2:2.4                                                                              7:3.5                                                                            7:7                                                                               >200                                            A9675                                                                          __________________________________________________________________________      .sup.a Mice treated orally at 0 and 2 hours postinfection.                     .sup.b Amoxicillin: BLP2024 combinations were soluble in 50% DMSO.             Amoxicillin was soluble in TCMC (aqueous Tweencarboxymethylcellulose)          whereas BLP2024 was administered as a suspension in that vehicle         

                                      TABLE 8                                      __________________________________________________________________________     Oral Mouse Blood Levels of BL-P2036 and BL-P2013 or BL-P2024                              Blood Levels (mcg/ml)                                               Dose       15   30   60   90   120  150                                        Compound                                                                             (mg/kg)                                                                             Minutes After Administration                                        __________________________________________________________________________     Test Number 1                                                                  BL-P2036                                                                             25   1.7  2.3  0.9  <0.6 <0.6 <0.6                                                  (1.3-2.3)                                                                             (2-2.6)                                                                           (0.6-1.3)                                                 BL-P2036                                                                             50   2.8  3.3  2.5  1.3  0.8  <0.6                                                  (1.6-4.8)                                                                             (2-5.3)                                                                           (1.2-5.3)                                                                           (0.7-2.4)                                                                           (0.5-1.5)                                       BL-P2036                                                                             100  3.6  3.9  3.2  2    1.5  0.8                                                   (2.6-4.9)                                                                           (2.9-5.1)                                                                           (2.4-4.4)                                                                           (1.5-2.7)                                                                           (1.1-2.1)                                                                           (0.7-1.0)                                  BL-P2013                                                                             25   1.3  1.4  1.0  <0.6 <0.6 <0.6                                                  (1.1-1.6)                                                                           (1.2-1.6)                                                                           (0.8-1.2)                                                 BL-P2013                                                                             50   2.2  2.6  1.9  1.5  1.1  0.8                                                   (1.8-2.7)                                                                           (2.1-3.2)                                                                           (1.4-2.6)                                                                           (1.1-2.1)                                                                           (0.8-1.4)                                                                           (0.5-1.3)                                  BL-P2013                                                                             100  3.4  4.5  3.9  3.6  2.7  2.1                                                   (2.1-5.4)                                                                           (3.6-5.7)                                                                           (3.4-4.6)                                                                           (2.5-5)                                                                             (1.7-4.3)                                                                           (1.4-3.2)                                  Test Number 2                                                                  BL-P2024                                                                             25   3.7  4.3  2.3  0.8  <0.6 >0.6                                                  (2.6-5.5)                                                                           (3-6.2)                                                                             (0.9-5.8)                                                                           (0.4-1.8)                                            BL-P2024                                                                             50   5    4.5  4.9  3.6  2.6  1.7                                                   (0.8-33.3)                                                                          (1.5-13.4)                                                                          (2.4-9.8)                                                                           (3.1-4.1)                                                                           (1.5-4.3)                                                                           (0.9-3.1)                                  BL-P2024                                                                             100  8.3  9.5  7.8  4.8  3.9  3.7                                                   (5.5-12.6)                                                                          (5.2-17.5)                                                                          (4.2-14.3)                                                                          (3.4-6.7)                                                                           (2.2-6.8)                                                                           (2.8-5)                                    BL-P2036                                                                             25   3.6  3.3  2.1  1.4  0.8  <0.6                                                  (2.2-5.9)                                                                           (2.2-4.7)                                                                           (1.6-2.8)                                                                           (0.7-2.8)                                                                           (0.4-1.7)                                       BL-P2036                                                                             50   4.0  3.6  2.2  2.1  1.5  1.0                                                   (3-5.3)                                                                             (1.4-9)                                                                             (1.4-3.7)                                                                           (1.3-3.6)                                                                           (0.6-3.6)                                                                           (0.5-2.4)                                  BL-P2036                                                                             100  4.9  6.5  4.5  2.8  1.9  1.3                                                   (3.7-6.5)                                                                           (3.7-11.5)                                                                          (3.4-5.9)                                                                           (2.2-3.6)                                                                           (1-3.7)                                                                             (0.4-4)                                    Test Number 3                                                                  BL-P2013                                                                             25   1.4  2.0  1.4  1.2  <1.2 <1.2                                                  (1.1-1.9)                                                                           (1.5-2.6)                                                                           (0.9-2.1)                                                                           (0.6-2.3)                                            BL-P2013                                                                             50   4.6  5.5  3.6  3.1  2    1.1                                                   (3-6.9)                                                                             (3-10.1)                                                                            (2-6.4)                                                                             (1.7-5.7)                                                                           (0.8-5)                                                                             (0.8-1.5)                                  BL-P2013                                                                             100  6.8  11.5 6.4  4.2  3.3  2.5                                                   (4.8-9.6)                                                                           (7.3-18)                                                                            (3.2-12.8)                                                                          (2.1-8.6)                                                                           (1.4-7.6)                                                                           (0.7-8.9)                                  BL-P2036                                                                             25   4.3  4.5  3.5  2.5  2.2  2.0                                                   (2.9-6.5)                                                                           (2.2-9.2)                                                                           (1.7-7.2)                                                                           (1.3-4.8)                                                                           (1-4.9)                                                                             (1-3.7)                                    BL-P2036                                                                             50   4.6  4.8  3.5  2.2  1.9  1.8                                                   (2.3-9.2)                                                                           (3.3-7.1)                                                                           (1.8-7)                                                                             (1.2-4)                                                                             (1.2-3)                                                                             (0.3-4.6)                                  BL-P2036                                                                             100  7.1  6.7  5.8  4.3  4    2.7                                                   (3.1-16.2)                                                                          (3.6-12.3)                                                                          (3.9-8.5)                                                                           (3-6)                                                                               (2.8-5.6)                                                                           (1.8-4)                                    __________________________________________________________________________      Compounds prepared in 5% Propylene Glycol & TweenCMC-H.sub.2 O.                Values in parentheses are 95% confidence limits.                               Assay Organism: E. coli A9675 (pH = 6.6, 0.1% inoculum)                  

The compounds of the present invention are thus useful, given orally and parenterally, for enhancing the effectiveness of β-lactam antibiotics against β-lactamase producing bacteria. On a weight basis, the dosage is from one-fifth to five times, and preferably equal to, that of the β-lactam antibiotics. As an example, the compounds of the present invention as shown above when used in a 1:1 ratio markedly improved the activity of ceforanide and amoxicillin against β-lactamase producing strains of anaerobic Bacteroides such as B. fragilis, B. thetaiotaomicron and other species of that genus and also against resistant Staphylococcus aureus. The compounds of the present invention are given either in admixture with or concomitantly with the β-lactam antibiotic with the dosage within the indicated ratio to the known and customary dosage of the antibiotic.

Thus, the ability of the compounds of the present invention to enhance the effectiveness of a β-lactam antibiotic against certain β-lactamase-producing bacteria makes them valuable for co-administration with certain β-lactam antibiotics in the treatment of bacterial infections in mammals, particularly man. In the treatment of a bacterial infection, a compound of the present invention can be comingled with the β-lactam antibiotic, and the two agents thereby administered simultaneously. Alternatively, a compound of the present invention can be administered as a separate agent during a course of treatment with a β-lactam antibiotic.

When using a compound of the present invention or salt thereof, to enhance the antibacterial activity of a β-lactam antibiotic, it can be administered alone, or preferably, in formulation with standard pharmaceutical carriers and diluents. A compound of the present invention which is in the acid form or as a pharmaceutically-acceptable salt thereof, can be administered orally or parenterally; a compound of the present invention in the form of an ester which is readily hydrolyzable in vivo, is best administered orally. Parenteral administration includes intramuscular, subcutaneous, intraperitoneal and intravenous administration.

When a compound of the present invention is used in the presence of a carrier or diluent, said carrier or diluent is chosen on the basis of the intended mode of administration. For example, when considering the oral mode of administration, the compound can be used in the form of tablets, capsules, lozenges, troches, powders, syrups, elixirs, aqueous solutions and suspensions, and the like, in accordance with standard pharmaceutical practice. The proportional ratio of active ingredients to carrier will naturally depend on the chemical nature, solubility, stability and potency of the active ingredients, as well as the dosage contemplated. However, these pharmaceutical compositions will likely contain from about 5% to about 80% of carrier. In the case of tablets for oral use, carriers which are commonly used include lactose, sodium citrate and salts of phosphoric acid. Various disintegrants such as starch, and lubricating agents, such as magnesium stearate, sodium lauryl sulfate and talc, are commonly used in tablets. For oral administration in capsule form, useful diluents are lactose and high molecular weight polyethylene glycols. When aqueous suspensions are required for oral use, the active ingredients are combined with emulsifying and suspending agents. If desired, certain sweetening and/or flavoring agents can be added. For parenteral administration, which includes intramuscular, intraperitoneal, subcutaneous and intravenous use, sterile solutions of the active ingredients are usually prepared, and the pH or the solutions are suitably adjusted and buffered. For intravenous use, the total concentration of solutes should be controlled to render the preparation isotonic.

Although the prescribing physician will ultimately decide the dosage to be used in a human subject, the ratio of the daily dosages of a compound of the present invention, or salt thereof, and the β-lactam antibiotic will normally be in the range from about 1:5 to 5:1, and preferably about 1:1. Additionally, the daily dosage of each component will normally be in the range from about 10 to about 200 mg. per kilogram of body weight and the daily parenteral dosage of each component will normally be about 10 to about 100 mg. per kilogram of body weight. These figures are illustrative only, however, and in some cases it may be necessary to use dosages outside these limits.

This invention is capable of industrial application. 

I claim:
 1. An ester having the formula ##STR59## wherein R is benzyl or p-nitrobenzyl.
 2. The ester of claim 1 wherein R is p-nitrobenzyl.
 3. An ester having the formula ##STR60## wherein R is benzyl, p-nitrobenzyl or β,β,β-trichloroethyl.
 4. The ester of claim 3 wherein R is p-nitrobenzyl.
 5. The ester of claim 3 wherein R is β,β,β-trichloroethyl.
 6. The ester having the formula ##STR61## 